function formatTimestamp(timestamp, period) {
  var d = new Date(timestamp);
  if (period == 'instant') {
    return $.plot.formatDate(d, '%b %d, %h:%M %p');
  } else if (period == 'daily') {
    return $.plot.formatDate(d, '%b %d');
  } else if (period == 'weekly') {
    // A bit more complicated than the above: the timestamp is in the
    // middle of the week, so we have to bracket the date. This is
    // something of a fudge here, but it works well enough.
    var start = new Date(d.getTime() - 3 * 24 * 60 * 60 * 1000);
    var end = new Date(d.getTime() + 3 * 24 * 60 * 60 * 1000);
    return (
      $.plot.formatDate(start, '%b %d') +
      ' - ' +
      $.plot.formatDate(end, '%b %d')
    );
  }
}

function convertSecondsToMilliseconds(data) {
  for (var i = 0; i < data.length; i++) {
    data[i][0] = data[i][0] * 1000;
  }
  return data;
}
